Maech 19, 1S97.] 



SCIENCE. 



483 



of muscular contraction, is now supported by 

 results obtained through the study of the elec- 

 trical changes set up in muscle by artificial 

 stimulation. In brief, the chemical changes of 

 disassimilation, coincident with functional ac- 

 tivity, which are brought about by stimulation 

 of the motor nerve, cause the active part of the 

 tissue to become electro-negative to the resting 

 part. 



On the other hand, certain other efferent 

 nerves, having an inhibitory effect, cause, when 

 stimulated, the part of the muscle under their 

 influence to become electro-positive to the rest- 

 ing part. In all probability these nerves also ex- 

 cite chemical assimilation and the absorption of 

 energy. 



It is approaching an anti-climax to turn from 

 such a conception as this to the arid field of 

 glandular electricity. Here the mechanical 

 difficulties in the way of experimentation have 

 affected the purity of results to such a degree 

 that little of physiological importance can, as 

 yet, be predicated from the work. In conclu- 

 sion, a word of admiration is due the translator 

 to whose fortitude we are indebted for this work 

 in its present form. The rendition seems, for 

 the most part, to be excellent ; and the book- 

 making by Macmillan is, of course, of the best. 



Heney Sewall. 

 Univbesity or Denvee. 



The Coming Ice Age. By C. A. M. Tabee. 



Geo. H. Ellis. 1896. Pp. 94. 



The difficulty of accounting for the Glacial 

 period is so great and the disagreement of 

 glacialists is so profound that one cannot but 

 ■welcome any sincere effort to shed additional 

 light upon the subject. Especially is one in- 

 clined to give a candid hearing to an experi- 

 enced navigator who has been led to study the 

 effects of ocean currents upon climatic condi- 

 tions. Such is the author of this little volume, 

 who, in his extensive voyages had his attention 

 directed to the subject at an early date, and in 

 later years has made his personal observations 

 the basis for collecting a large body of facts 

 otherwise attainable. 



The theory of the author is that a land con- 

 nection between Patagonia and the Antarctic 

 Continent, or a great diminution of the channel 



between those lands, would produce an effect 

 upon oceanic currents favorable to the glacia- 

 tiou of both hemispheres. In supposing such a 

 land connection he is in company with many 

 zoologists who have inferred the same from the 

 unique distribution of the plants and animals of 

 the southern hemisphere. 



Assuming this extension of land from Pata- 

 gonia to the Antarctic Continent, the effect 

 upon the currents would be, according to the 

 author, as follows: The prevailing westerly 

 winds in the south temperate zone would pile 

 the waters up against the western side, and 

 would drive them away from the eastern side 

 of the southern part of this continent. The 

 shape of the continents and the general direc- 

 tion of ocean currents are such that during this 

 condition of things there would be a movement 

 of water towards the south pole in excess of that 

 moving toward the north pole. This accumu- 

 lation of water about the south pole would be 

 increased by the attraction of the water until 

 there was a submergence of the isthmus con- 

 necting Patagonia with the Antarctic Continent, 

 such as to allow a free passage from the higher 

 levels of the Pacific to the lower levels of the 

 Atlantic in that latitude. This water from the 

 Pacific, being a cold current, would displace 

 that which had formerly been drawn down 

 from the tropics on the east side of South 

 America, and thus lower the temperature of 

 the Antarctic Continent and produce conditions 

 favorable to glaciation, such as exist at the 

 present time. These conditions he believes to 

 be cumulative. 



This very general statement of the theory 

 passes over many details, and it may be that it 

 does not in all respects fairly represent the 

 author's views. But we are compelled to confess 

 that his style is so obscure, and his digressions 

 are so frequent, that we have found it difficult 

 to be sure that we have comprehended his 

 meaning. The author's confidence in the sta- 

 bility of the earth's crust is such that he is not 

 willing to grant the moderate changes of level 

 in the sea-bottom south of Patagonia which 

 would be necessary to secure the submergence 

 there which his theory demands ; therefore, he 

 is compelled to throw the whole burden upon 

 the winds and the augmenting attraction of the 



